1. Field of the Invention
The invention relates to an apparatus for taking a sample from at least one fluid system and for passing the at least one sample taken to an analytical evaluation system.
2. Description of the Related Art
An apparatus for taking a sample from at least one fluid system and for passing the at least one sample taken to an analytical evaluation system, having at least one sample-taking cylinder with a sample-taking piston guided on it is known from DE 39 20 946 C2.
DE 10 2004 004 342 A1, U.S. Pat. Nos. 5,088,335 A, 5,717,131 A, 6,419,127 B1, DE 100 61 725 B4, U.S. Pat. No. 2,388,662 A, DE 41 25 141 C2, DE 199 37 026 A1, EP 0 022 654 A1, and U.S. Pat. No. 5,736,654 A show various further apparatuses for taking fluid samples.
Taking fluid samples from a gaseous or liquid fluid system, which can involve a flowing or stationary volume, and subsequently passing the samples to an analytical evaluation system, for example a mass spectrometer or an ion mobility spectrometer, preferably with prior separation (for example by means of gas chromatography, liquid chromatography or electrophoresis), is of great importance for many applications, for example process control, diagnostics from respiratory air, head space analysis and many more.
For this purpose, in the simplest case, a fluid sample is taken from the fluid system using a syringe or the like, concentrated if necessary, and transported to a laboratory, where it is transferred to an analysis system. This method of procedure is time-consuming and cost-intensive; the analysis result is often available only with a clear time delay (hours to days). For this reason, quasi on-line methods are increasingly being used. For example, a sample from a volume or volume stream is drawn into a sample volume using a pump, for example, and this volume is then injected into the pre-separation unit of the analysis system by means of a carrier flow. It is true that such a method is clearly faster, but it requires flushing the sample volume for an appropriate period of time, in order to displace the previously existing volume, as well as flushing the sample volume into the pre-separation unit. This corresponds, in principle, to exponential dilution of the sample (flushing out a high initial concentration, which leads to an exponential decrease in concentration) during injection, with the result that the signals are delayed or, if the flushing-in process is broken off, a loss of part of the sample occurs after a certain period of time.